Core Web Vitals are three measurements Google uses to judge how your site feels to real visitors. They’re part of Google’s page experience signals, and more importantly, they track closely with whether people stay or leave.
Google measures them from real Chrome users visiting your site, and judges you at the 75th percentile. That means your site needs to be fast for most visitors, not just on your office Wi-Fi.
LCP: how fast the main content appears
Largest Contentful Paint measures how long it takes for the biggest thing on screen, usually a hero image or headline, to show up. Good is 2.5 seconds or less.
- Compress and resize images, and serve modern formats like WebP or AVIF.
- Don’t lazy-load the main hero image; load it first.
- Use good hosting and a CDN so pages start arriving quickly.
INP: how fast the page responds
Interaction to Next Paint measures how quickly your page reacts when someone taps a button, opens a menu or types in a field. Good is 200 milliseconds or less. INP replaced the older First Input Delay metric in March 2024.
- Cut unused plugins and third-party scripts, like old chat widgets and tracking pixels.
- Break up heavy JavaScript so the browser isn’t tied up.
- Be wary of page builders that load a lot of code on every page.
CLS: how much the page jumps around
Cumulative Layout Shift measures unexpected movement, like when you go to tap a link and an ad loads above it. Good is 0.1 or less.
- Set width and height on images and videos so space is reserved.
- Reserve space for banners, embeds and ads before they load.
- Load web fonts in a way that doesn’t reflow text.
How much does it matter for rankings?
Honestly: great content on a slow site will usually outrank thin content on a fast one. But when competitors are close, page experience can be the tiebreaker, and speed has a much bigger effect on whether visitors call you once they arrive.
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Founder and lead developer of DigitalRocket in Syracuse. Jon has spent more than 20 years building websites and software, including over a decade at Syracuse advertising agencies, and now helps Central New York businesses put AI to work, connect their tools with custom software, and run fast, secure websites.